The following discussion of the background of the disclosure is merely provided to aid the reader in understanding the disclosure and is not admitted to describe or constitute prior art to the present disclosure.
Nearly 1 out of 6 couples in the U.S. seeking to have children experience infertility. For those who have been unsuccessful conceiving a child with the aid of pharmaceuticals, surgery, or artificial insemination, in vitro fertilization (IVF) is their best option to finally become pregnant. However, the average live-birth rate for an IVF cycle is approximately 1-in-3 and this rate has only modestly increased since the advent of IVF more than 30 years ago.
An IVF cycle consists of hormonal stimulation so that several eggs can be surgically harvested, and then these ova are fertilized in vitro so that they can develop in culture for evaluation. Typically after three days, the embryos are examined under the microscope by the embryologist to select the most viable embryos to transfer back to the mother. The embryologist faces a significant dilemma where he or she must select which of these available embryos is viable, based on morphological assessment.
Ideally, only one embryo should be transferred back to the mother to eliminate the risks associated with multiple gestation pregnancies such as pre-term birth, low birth weight, and the necessity for fetal reduction in some cases. Due to the subjective and inaccurate nature of this morphological assessment, however, multiple embryos are transferred back to the mother in 90% of cases in order to increase the chances for a successful implantation.
Another IVF technique extends the length of embryo culture to five days which is the blastocyst stage (Behr et al., Human Reproduction, 14(2):454-7, 1999). The embryos that survive to the blastocyst stage are thought to be more viable and therefore have a higher rate of implantation. Culturing to the day-five blastocyst stage has been used clinically to transfer fewer embryos but has also demonstrated how poor the more common day-three selection is in predicting survival.
Moreover, unfortunately, not all women qualify for blastocyst transfer because they may not have a sufficient number of embryos at day-three to risk further attrition. Even for those who do qualify, blastocyst transfer is still controversial as some propose that embryos should be transferred earlier to avoid undue stress on the embryos. Therefore, embryologists need an objective and quantitative measure of embryo viability at an early stage to improve a patient's chance of achieving a single live-birth.